Thanks for the great question! We actually use a reasoning-based, vectorless approach. In short, it follows this process:

  1. Generate a table of contents (ToC) for the document.

  2. Read the ToC to select a relevant section.

  3. Extract relevant information from the selected section.

  4. If enough information has been gathered, provide the answer; otherwise, return to step 2.

We believe this approach closely mimics how a human would navigate and read long PDFs.